Merge pull request #811 from niccokunzmann/issue-218

Fix broken ical with a date as DTSTART in timezone definition

Author: niccokunzmann

CHANGES.rst

@@ -30,6 +30,7 @@ New features:
 
 Bug fixes:
 
+- Fix ``STANDARD`` and ``DAYLIGHT`` components that have a date as ``DTSTART``. See `Issue 218 <https://github.com/collective/icalendar/issues/218>`_
 - Move import at the end of ``icalendar.parser`` into a function to mitigate import errors, see `Issue 781 <https://github.com/collective/icalendar/issues/781>`_.
 - ``ALTREP``, ``DELEGATED-FROM``, ``DELEGATED-TO``, ``DIR``, ``MEMBER``, and ``SENT-BY`` require double quotes. These are now always added.
 - Classify ``CATEGORIES`` as multiple in ``VEVENT``. See `PR 808 <https://github.com/collective/icalendar/pull/808>`_.

src/icalendar/cal.py

@@ -40,7 +40,7 @@
     vUTCOffset,
 )
 from icalendar.timezone import TZP, tzp
-from icalendar.tools import is_date
+from icalendar.tools import is_date, to_datetime
 
 if TYPE_CHECKING:
     from icalendar.alarms import Alarms
@@ -1232,6 +1232,8 @@ class Timezone(Component):
     way in which a time zone changes its offset from UTC over time.
     """
 
+    subcomponents: list[TimezoneStandard|TimezoneDaylight]
+
     name = "VTIMEZONE"
     canonical_order = ("TZID",)
     required = ("TZID",)  # it also requires one of components DAYLIGHT and STANDARD
@@ -1359,6 +1361,8 @@ def get_transitions(
         for component in self.walk():
             if type(component) == Timezone:
                 continue
+            if is_date(component["DTSTART"].dt):
+                component.DTSTART = to_datetime(component["DTSTART"].dt)
             assert isinstance(
                 component["DTSTART"].dt, datetime
             ), "VTIMEZONEs sub-components' DTSTART must be of type datetime, not date"

src/icalendar/tests/calendars/issue_218_bad_tzid.ics

@@ -0,0 +1,24 @@
+BEGIN:VCALENDAR
+VERSION:2.0
+PRODID:-//TEST//TEST//EN
+BEGIN:VTIMEZONE
+TZID:UTC+11
+BEGIN:STANDARD
+DTSTART;VALUE=DATE:20170101
+TZNAME:UTC+11
+TZOFFSETFROM:+1100
+TZOFFSETTO:+1100
+END:STANDARD
+END:VTIMEZONE
+BEGIN:VEVENT
+DESCRIPTION:TESTING
+DTEND;TZID=UTC+11:20170228T233000
+DTSTAMP:20170227T064302Z
+DTSTART;TZID=UTC+11:20170228T230000
+RESOURCES:Court 4
+SEQUENCE:0
+STATUS:Confirmed
+SUMMARY:TESTIN
+UID:1961094_636238800000000000
+END:VEVENT
+END:VCALENDAR

src/icalendar/tests/test_issue_218_parse_calendar.py

@@ -0,0 +1,32 @@
+"""Parse the calendar and make sure the timezone is used.
+
+See https://github.com/collective/icalendar/issues/218
+"""
+from __future__ import annotations
+
+from datetime import datetime, timedelta
+from typing import TYPE_CHECKING
+
+import pytest
+
+from icalendar.timezone.tzid import tzid_from_dt
+
+if TYPE_CHECKING:
+    from icalendar import Event
+
+@pytest.fixture()
+def event(calendars) -> Event:
+    """The event to check."""
+    return calendars.issue_218_bad_tzid.events[0]
+
+
+def test_event_has_start_and_end(event : Event):
+    """The calendar should be parsed and the start and end have a timezone."""
+    assert event.start.replace(tzinfo=None) == datetime(2017, 2, 28, 23, 00)
+    assert event.end.replace(tzinfo=None) == datetime(2017, 2, 28, 23, 30)
+
+def test_timezone(event:Event):
+    """The event uses a timezone."""
+    assert event.start.tzinfo == event.end.tzinfo
+    assert tzid_from_dt(event.start) == "UTC+11"
+    assert event.start.utcoffset() == timedelta(hours=11)

src/icalendar/timezone/zoneinfo.py

@@ -2,6 +2,8 @@
 
 from __future__ import annotations
 
+from icalendar.tools import is_date, to_datetime
+
 try:
     import zoneinfo
 except ImportError:
@@ -21,6 +23,7 @@
 
 if TYPE_CHECKING:
     from icalendar import cal, prop
+    from icalendar.prop import vDDDTypes
 
 
 class ZONEINFO(TZProvider):
@@ -72,6 +75,11 @@ def create_timezone(self, tz: cal.Timezone) -> tzinfo:
                 for attr in list(sub.keys()):
                     if attr.lower().startswith("x-"):
                         sub.pop(attr)
+            for sub in tz.subcomponents:
+                start : vDDDTypes = sub.get("DTSTART")
+                if start and is_date(start.dt):
+                    # ValueError: Unsupported DTSTART param in VTIMEZONE: VALUE=DATE
+                    sub.DTSTART = to_datetime(start.dt)
             return self._create_timezone(tz)
 
     def _create_timezone(self, tz: cal.Timezone) -> tzinfo: